Modelling of AC losses and fields in high temperature superconducting tapes
Modelling of AC losses and fields in high temperature superconducting tapes
This thesis is concerned with the modelling and the computation of AC losses and electromagnetic fields in high temperature superconducting tapes using an E - J characteristics diffusion model.
The AC losses in high temperature superconductors are modelled as a highly non-linear diffusion process. An empirical expression for modelling effective resistivity of the tape is extracted from the Rhyner's model and then used in the build up of the diffusion model. Formulation in terms of electric field E is used extensively and comprehensive explanations of why this model is used are given. Using the E formulation three different models that describe three different cases of the problem are developed.
To understand the physical and numerical phenomena that occur when a superconducting tape carries an alternating current or is exposed to an external variable magnetic field a one-dimensional model has been developed first. Comprehensive details and results of the principle and formulation of the primary model are given. The solid basis created by the one-dimensional model and the necessity of the model to be closer to the real tape drive us to two more realistic models, one where a silver layer is added on the top of the superconducting core, and the second one is the two-dimensional model where the edge effects and importance of non-linearity is emphasised. For both of these models comprehensive formulations and results are given.
A collection of programs that solves the models has been created and tested, and the results obtained where successfully compared with results obtained by other authors through numerical and experimental means.
The research demonstrates that the models developed are useful in exploring the mechanism of AC losses in superconducting tapes, the numerical programs allow prediction of losses under particular conditions and the applicability of different models (one and two-dimensional, the "sandwich model" and the critical state model respectively).
University of Southampton
2000
Rotaru, Mihai Dragos
(2000)
Modelling of AC losses and fields in high temperature superconducting tapes.
University of Southampton, Doctoral Thesis.
Record type:
Thesis
(Doctoral)
Abstract
This thesis is concerned with the modelling and the computation of AC losses and electromagnetic fields in high temperature superconducting tapes using an E - J characteristics diffusion model.
The AC losses in high temperature superconductors are modelled as a highly non-linear diffusion process. An empirical expression for modelling effective resistivity of the tape is extracted from the Rhyner's model and then used in the build up of the diffusion model. Formulation in terms of electric field E is used extensively and comprehensive explanations of why this model is used are given. Using the E formulation three different models that describe three different cases of the problem are developed.
To understand the physical and numerical phenomena that occur when a superconducting tape carries an alternating current or is exposed to an external variable magnetic field a one-dimensional model has been developed first. Comprehensive details and results of the principle and formulation of the primary model are given. The solid basis created by the one-dimensional model and the necessity of the model to be closer to the real tape drive us to two more realistic models, one where a silver layer is added on the top of the superconducting core, and the second one is the two-dimensional model where the edge effects and importance of non-linearity is emphasised. For both of these models comprehensive formulations and results are given.
A collection of programs that solves the models has been created and tested, and the results obtained where successfully compared with results obtained by other authors through numerical and experimental means.
The research demonstrates that the models developed are useful in exploring the mechanism of AC losses in superconducting tapes, the numerical programs allow prediction of losses under particular conditions and the applicability of different models (one and two-dimensional, the "sandwich model" and the critical state model respectively).
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Published date: 2000
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Local EPrints ID: 464212
URI: http://eprints.soton.ac.uk/id/eprint/464212
PURE UUID: e8a3ec42-00e5-4df3-813a-920582a81810
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Date deposited: 04 Jul 2022 21:35
Last modified: 04 Jul 2022 21:35
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Author:
Mihai Dragos Rotaru
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